172 



occur before the Mnd-feet leave the ground instead 

 of, as in the trot, just as they have done so.* 



§ 156. The Canterj- or Gallop. There remains still 

 this other perfect gait, which is the usual method 

 of locomotion in double action. 



If we consider the double trot, in reference to 

 the alternate expanding and contracting of the 

 lung lobes, it will be seen that, in the gatherings,, 

 there is a very forcible expansion of them, in which 

 state they are retained to await the movement of 

 the breast-bone (or " substitute gi'ound"). This is 

 evidently a laborious action, as may be observed 

 when putting a horse through the movement. On 

 the other hand, although the double pace is easier, 

 because the extreme tension comes on only at the 

 moment when the completion of the final diagonal 

 actions enables the lungs readily to relieve them- 

 selves at the spring, and makes this gait the one 

 for the highest speed. Yet, since it requires a 

 complete leaving of the ground by aU four 

 appuis at the same moment, and gives no inter- 

 mediate instant of rest on two appuis, it calls for a 

 great expenditure of force. 



* It must be necessary for the lion, &c., when carrying a weight 

 in the mouth, that the condyles and lower jaw should take their alternate^ 

 bearings before the body leaves the ground. 



t We shall use the term canter as more definite than gallop. 



